Copulatory organs are absent, except in the Apoda, in which a portion of the cloaca can be everted and acts as a penis.
Internally they are found to consist of a lamina twisted upon itself, and externally they generally exhibit a tortuous structure, produced, before the cloaca was reached, by the spiral valve of a compressed small intestine (as in skates, sharks and dog-fishes); the surface shows also vascular impressions and corrugations due to the same cause.
In forms living in a tube the intestine turns round and runs forward, the cloaca being placed so as to debouch over the margin of the tube.
The cloaca is divided by transverse circular folds, which project from its inner walls, into three successive chambers.
It is necessary to use geographical terms in the case of California and the North Pacific, the Caucasus or cloaca gentium of the western hemisphere, where were pocketed forty out of one hundred or more families of native tribes.
It is significant that the whole type of their cloaca much resembles that of the Crocodilia and Chelonia, in opposition to that of the Lacertilia.
The extraing to foot of rotifers; at, median blastoporic opening of antenna, united by a nerve to br, brain the cloaca leads us to a (letter omitted in B); bl, bladder, re ver y different view, which ceiving ramified kidney in B, C, D; finds negative support f, foot, and f.g, its cement-gland;.
In the great majority of birds it has disappeared completely and the primitive way of everting the cloaca is resorted to.
Trophi virgate exsertile; germary paired; genito-urinary cloaca opening above the neck in the male, subapically in the female.
Other newts, and many salamanders, whether terrestrial or aquatic, pair, the male embracing the female about the fore limbs or in the pelvic region, and the males of such forms are invariably devoid of ornamental secondary sexual characters; but in spite of this amplexation the same mode of fecundation by means of a spermatophore is resorted to, although it may happen that the contents of the spermatophore are absorbed direct from the cloaca of the male.